Polymer membranes for continuous analyte sensors

Abstract

Devices and methods are described for providing continuous measurement of an analyte concentration. In some embodiments, the device has a sensing mechanism and a sensing membrane that includes at least one surface-active group-containing polymer and that is located over the sensing mechanism. The sensing membrane may have a bioprotective layer configured to substantially block the effect and/or influence of non-constant noise-causing species.

What is claimed is: 
     
       1. A device for continuous measurement of an analyte concentration, the device comprising:
 a sensor configured to continuously measure a signal associated with an analyte concentration in a host; and 
 a membrane located over the sensor, wherein the membrane comprises a polyurethane and a hydrophilic portion; 
 wherein the device is configured to provide, at analyte concentrations of from about 40 mg/dL to about 400 mg/dL, a level of accuracy corresponding to a mean absolute relative difference of no more than 8% over a sensor session of at least about 3 days, wherein one or more reference measurements associated with calculation of the mean absolute relative difference are determined by analysis of blood. 
 
     
     
       2. The device of  claim 1 , wherein the sensor session is at least about 5 days. 
     
     
       3. The device of  claim 1 , wherein the sensor session is at least about 6 days. 
     
     
       4. The device of  claim 1 , wherein the sensor session is at least about 7 days. 
     
     
       5. The device of  claim 1 , wherein the sensor session is at least about 10 days. 
     
     
       6. The device of  claim 1 , wherein the membrane comprises a copolymer comprising a silicone segment. 
     
     
       7. The device of  claim 1 , wherein the mean absolute relative difference is no more than 7% over the sensor session. 
     
     
       8. The device of  claim 1 , wherein the membrane comprises an enzyme configured to react with the analyte. 
     
     
       9. The device of  claim 1 , wherein the membrane comprises a copolymer comprising a fluorocarbon segment. 
     
     
       10. The device of  claim 1 , wherein the membrane comprises a polycarbonate segment. 
     
     
       11. The sensor of  claim 1 , wherein the sensor is configured for transcutaneous implantation into a host. 
     
     
       12. The sensor of  claim 1 , wherein the sensor comprises a first portion and second portion, wherein the first portion is adapted for insertion under the host's skin and the second portion is adapted to reside ex vivo. 
     
     
       13. The sensor of  claim 1 , wherein the sensor is configured to reside in subcutaneous tissue. 
     
     
       14. The sensor of  claim 1 , wherein the sensor is configured to have a mean absolute difference of no more than 7 mg/dL at an analyte concentration range of from 40 mg/dL to 80 mg/dL. 
     
     
       15. The sensor of  claim 1 , wherein the host is diabetic. 
     
     
       16. The sensor of  claim 1 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 30 mg/dL while immersed in a solution comprising about 3 mg/dL acetaminophen. 
     
     
       17. The sensor of  claim 1 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 17 mg/dL while immersed in a solution comprising about 6 mg/dL ascorbic acid. 
     
     
       18. The sensor of  claim 1 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 25 mg/dL while immersed in a solution comprising about 6 mg/dL uric acid. 
     
     
       19. A system for continuous measurement of an analyte concentration, the system comprising:
 a sensor comprising:
 a sensing region configured to continuously produce sensor data associated with an analyte concentration in a host; and 
 a membrane located over the sensing region, wherein the membrane comprises a polyurethane and a hydrophilic portion; 
 
 a processor configured to process continuous sensor data; and 
 a user interface configured to display information associated with continuous sensor data; 
 wherein the sensor is configured to provide, at analyte concentrations of from about 40 mg/dL to about 400 mg/dL, a level of accuracy corresponding to a mean absolute relative difference of no more than 8% over a sensor session of at least about 3 days, wherein one or more reference measurements associated with calculation of the mean absolute relative difference are determined by analysis of blood. 
 
     
     
       20. The system of  claim 19 , wherein the sensor session is at least about 5 days. 
     
     
       21. The system of  claim 19 , wherein the sensor session is at least about 6 days. 
     
     
       22. The system of  claim 19 , wherein the sensor session is at least about 7 days. 
     
     
       23. The system of  claim 19 , wherein the sensor session is at least about 10 days. 
     
     
       24. The system of  claim 19 , wherein the mean absolute relative difference is no more than 7% over the sensor session. 
     
     
       25. The system of  claim 19 , wherein the membrane comprises an enzyme configured to react with the analyte. 
     
     
       26. The system of  claim 19 , wherein the membrane comprises a copolymer comprising a fluorocarbon segment. 
     
     
       27. The system of  claim 19 , wherein the membrane comprises a copolymer comprising a silicone segment. 
     
     
       28. The system of  claim 19 , wherein the membrane comprises a polycarbonate segment. 
     
     
       29. The system of  claim 19 , wherein the sensor is configured for transcutaneous implantation into a host. 
     
     
       30. The system of  claim 19 , wherein the sensor comprises a first portion and second portion, wherein the first portion is adapted for insertion under the host's skin and the second portion is adapted to reside ex vivo. 
     
     
       31. The system of  claim 19 , wherein the sensor is configured to reside in subcutaneous tissue. 
     
     
       32. The system of  claim 19 , wherein the sensor is configured to have a mean absolute difference of no more than 7 mg/dL at an analyte concentration range of from 40 mg/dL to 80 mg/dL. 
     
     
       33. The system of  claim 19 , wherein the host is diabetic. 
     
     
       34. The system of  claim 19 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 30 mg/dL while immersed in a solution comprising about 3 mg/dL acetaminophen. 
     
     
       35. The system of  claim 19 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 17 mg/dL while immersed in a solution comprising about 6 mg/dL ascorbic acid. 
     
     
       36. The system of  claim 19 , wherein the sensor is configured to exhibit no more than an equivalent glucose signal of no more than about 25 mg/dL while immersed in a solution comprising about 6 mg/dL uric acid.